Semi-Cylindrical LED Lens with Graded Fluorescent Material
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Solution Overview
Problem
Existing light emitting devices that combine blue light emitting diodes and fluorescent materials face challenges in controlling color tone due to variations in the amount of fluorescent material, leading to color unevenness and difficulties in manufacturing a low-profile, side-view type with favorable light distribution characteristics.
Innovation Solution
A light emitting device with a transparent layer forming a semi-cylindrical lens, where the fluorescent material is concentrated near the light emitting diode, and a two-layer structure with a first transparent layer containing the fluorescent material and a second transparent layer forming the lens, allowing for better light distribution and easier manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the fluorescent material is dispersed uniformly in the resin layer, then the manufacturing process is simple, but color unevenness occurs due to different light paths in different directions
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of fluorescent material within the resin layer. Specifically, the fluorescent material is concentrated in a first region closer to the light emitting diode with a higher concentration than in a second region farther away. This localized concentration variation resolves the color unevenness issue by ensuring that light rays traveling in different directions pass through comparable amounts of fluorescent material, while maintaining a relatively simple manufacturing process.
2Quantity of substance
If the resin layer is made thick to include sufficient fluorescent material, then the color tone can be controlled, but the device profile increases and light distribution characteristics deteriorate
Solution Approach 1:
The patent concentrates fluorescent material in a specific region (first region) closer to the light emitting diode rather than distributing it uniformly throughout a thick layer. This allows sufficient fluorescent material to be present for proper color tone control while keeping the overall resin layer thickness minimal, thus maintaining a low device profile and favorable light distribution characteristics.
Solution Approach 2:
The patent transitions from a uniform two-dimensional distribution of fluorescent material to a three-dimensional non-uniform distribution with concentration gradients. By varying the concentration in different spatial regions (higher near the LED, lower farther away), the patent achieves effective color control in a thinner overall structure.
3Illumination intensity
If the fluorescent material concentration is increased to control color tone, then the white light quality improves, but color unevenness in different viewing directions worsens
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatially varying fluorescent material concentration. The higher concentration in the first region ensures sufficient fluorescence for high-quality white light emission, while the gradient distribution (lower concentration in the second region) prevents excessive fluorescence for oblique light paths, thereby eliminating color unevenness across different viewing directions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves a low-profile light emitting device with improved light distribution characteristics and reduced color unevenness, enabling stable mounting and efficient light emission with high luminous intensity, while allowing for correction of color tone without affecting the lens shape.
Implementation Method 1
a fluorescent material that absorbs at least part of light emitted by the light emitting diode and converts it to light of a longer wavelength
Implementation Method 2
a lens that changes the direction of light emission from the light emitting diode and/or the fluorescent material
Data Source
AI summary
The light emitting device comprises a substrate (2), a positive electrode (6) and a negative electrode (4) formed on the substrate (2), a light emitting diode (8) connected to the positive electrode (6) and the negative electrode (4), the transparent resin (12 and 14) that covers the light emitting diode (8), a fluorescent material (16) that absorbs at least part of light emitted by the light emitting diode (8) and converts it to light of longer wavelength, and the lens that changes the direction of light emission from the light emitting diode (8) and/or the fluorescent material (16). The resin (12 and 14) includes the fluorescent material (16) and is formed so as to constitute the lens of substantially semi-cylindrical shape, and the fluorescent material (16) included in the resin (12 and 14) is distributed with a higher concentration in a region near the surface of the light emitting diode (8) than in a region near the surface of the portion that constitutes the lens.